Java - sub window button

Question

Google Chrome Recently an update was added that added an additional button to the top of the window, allowing you to change your account settings. I make excellent use of an extra button like this one, but I don't know how to do it. So how to add an extra button at the top of the window?

This is what I would like to do or keep in mind.

Answer 1

This is more of an amateurish / simple answer, but you can only make a title bar with all the drop-down lists without text until you reach the desired button and configure it